A railroad frog is an assembly of components or elements which is installed at the intersection of two trackwork running rails to permit the flanges of railroad flanged car wheels moving along one of the running rails to in effect pass across the other running rail without changing the elevation of the car wheel. The frog assembly supports the rim tread surface of each car wheel as it passes from an assembly wing rail component, across a gap-like flangeway element, and onto the frog point component when the wheel is moving in a "facing movement" direction. When moved in an opposite or "trailing movement" direction the tread of the flanged rail car wheel passes from being fully supported by the point element, across the same flangeway, and fully onto the wing rail element. The frog assembly flangeways are each essentially positioned intermediate the assembly point element and a respective one of the assembly wing elements.
It has long been observed that over prolonged periods the railroad industry's standard or conventional trackwork frog assembly, particularly as utilized in mainline turnouts and crossovers subject to high speed and/or heavy traffic, will experience and exhibit a crushing degradation of the frog point element tread surface in that zone where the frog tread surface areas are impacted by wheel loads as rail car wheels are moved and transferred from full support by the frog wing element to full support by the frog point element. To correct the observed deficiency it heretofore has been common practice to add wheel support material (to "pad out") to each of both sides of the V-shaped, frog point element starting at the element's 1/2-inch point location and in a tapered manner extending to either the point element's 3-inch spread location or 7-inch spread location. The material added to each side is essentially tapered from 1/8-inch width at the 1/2-inch point location to zero width at the applicable point element spread location, and does provide the point element with an increased cross-sectional area at its wheel transfer impact loading zone. However, such addition of wheel support material to each side of the frog point element, while desirably providing for increased point width and increased cross-sectional area at the frog point element zone of wheel transfer impact, unnecessarily complicates the process of machining the assembly's point element flangeways and also undesirably results in changes to the orientation of the point element's true gauge lines to a condition where they are not truly parallel to their respective adjacent frog wing element guard lines.
The extra point material commonly added along each theoretical gauge line reduces the trackwork rail gauge and also becomes a potential obstruction to the passage of wheel flanges. Further, the angle of taper of the added or pad material introduces a new lateral load to the trackwork frog structure. Accordingly, the heretofore common "pad out" modification overall makes the frog design difficult to machine, assemble, install, and gauge.
We have discovered that the standard railroad industry frog may be modified to produce a better so-called heavy point frog capability without adding material to or "padding out" the point element sides and thereby incurring the numerous disadvantages noted above. Such novel modification basically involves adding car wheel support material to increase the width of the frog wing elements at their guard lines rather than increase the width of the point element at its gauge lines. Doing such, while narrowing the width of the separation between the fog wing element guard lines and the frog point element gauge lines within an acceptable limit, does not invoke the penalties associated with the known or prior art frog point heavying modification.
As will be discussed hereinafter, the frog wing element guard line location modification functions to increase the tread surface width of the frog wing element and to simultaneously change the location of the center of the frog point element zone of wheel transfer to a position where the point element has greater width, greater cross sectional shear area, and greater resistance to point element tread surface damage otherwise caused by the impact loads of flanged rail car wheels passing through the frog.